The invention is an improved version of a conventional gravity closed, swing check valve. This type of valve has a solid clapper which pivots on a hinge pin between open and closed positions. When opening, rotation of the clapper is limited by contact with a stop, which may be the body of the valve or a protruding stop carried by the body, or a stop attached to the hinge itself.
The present invention was developed in connection with gravity closed, swing check valves which were being used in pressurized service in oilfield applications. It was noted in connection with these valves that they would commonly fail as a result of breakage of the hinge pin or deformation of the clapper.
Applicant surmised that this damage had two root causes. Firstly, surges of pressurized fluid flow would cause the clapper to open very quickly and with considerable force. And secondly, the contact area between the clapper and the stop was small, in some valve designs being only line contact. Thus the impact loading was concentrated.
Applicant concluded that a change in this respect might effectively reduce the damage. Applicant therefore set out to design a gravity closed, swing check valve that would have a relatively large contact area between the clapper and body in the fully open position, thereby better distributing the impact load and reducing local effects on the hinge pin and clapper.